Tri Electronics G-24 Portable 6-24k Gold Testing Made in the U.S.A. Tri Electronics new portable gold tester accurately tests both yellow and white gold jewelry and gives its results on an easy to read digital display. This unit uses an ecologically safe liquid to test yellow gold from 6 karat up to 24 karat and white gold from 6 karat to 18 karats. It reads "Not Gold" for anything below 6 karats. It operates on 3 AAA batteries (included) or with an optional AC/DC adapter. The Tri-Electronics G-24 Gold Tester has a 2-year manufacturer's warranty. Testing with the G-24 is fast and easy. For testing yellow gold, simply connect the testing clip to the G-24 body, make contact with the item being tested with the alligator clip testing plate*, clean the surface of the item to be tested and place a small drop of the ecologically safe liquid (one jar included) on the freshly cleaned surface of the item to be tested. Make sure the G-24 is switched on and the ready button is glowing red, and place the testing end of the G-24 over the small drop of liquid, making contact with the liquid. Push the test switch, and moments later, read the results on the display. Clean the item being tested and test again if you wish. For testing white gold, make sure the white gold testing mode is activated, which is done by pressing the test button before you test an item. This will light up a red dot on the display, which is the indication that you are in the white gold testing mode. The yellow gold testing mode is the default mode. Please read the instruction manual for details and limitations. All Tri-Electronic gold testers are made for accurately testing gold jewelry in its commonly made alloys.